Fungi associated with biological soil crusts in desert grasslands of Utah and Wyoming

Biological soil crusts of arid and semiarid regions of the world are recognized as one of the least explored niches occupied by fungi. The principal species of fungi associated with biocrusts in desert grasslands and their associated soils in two geographically separated sites were identified and compared with species from a similar community in which the active crust had been destroyed by grazing. The results confirm the existence of a highly diverse and to some degree a host specific assemblage (mycosociety) of fungi. Comparison of the prevalent species by presence and commonness at the undisturbed and disturbed sites revealed both quantitative and qualitative changes. The forms absent or with a markedly reduced occurrence in the disturbed site were three dark-colored anamorphs of loculoascomycetes (Bipolaris sp., Embellisia tellustris, Phoma anserina) and two loculoascomycetes (Graphyllium permundum, Pleospora richtophensis). Fungi present at all sites included Chrysosporium/Geomyces pannorum, Embellisia tellustris and Pseudozyma sp. Crust associated fungi not previously reported from soil included a basidiomycete (Cyphellostereum sp.), five loculoascomycetes (Kalmusia utahensis, Macroventuria wentii, Pleospora richtophensis, Phaeospora sp., Preussia sp.) and three mitosporic species (Heteroconium sp., Sclerococcum sp., Taeniolella sp.). Overall, the commonly encountered crust-associated fungi were dark-colored mitosporic and sterile forms apparently adapted to desert environments.